• D.A. Jaroszynski, M.P. Anania, E. Brunetti, S. Chen, S. Cipiccia, B. Ersfeld, J.P. Farmer, M.R. Islam, R.C. Issac, G. Raj, A. J. W. Reitsma, R.P. Shanks, G. Vieux, G.H. Welsh, S.M. Wiggins, X. Yang
  USTRAT/SUPA, Glasgow
• R.A. Bendoyro, F. Fiuza, M. Marti, J.L. Martins
  Instituto Superior Tecnico, Lisbon
• N. Bourgeois
  University of Oxford, Oxford
• J.M. Dias, N. Lemos, L.O. Silva
  GoLP, Lisbon
• P.S. Foster, R. Pattathil
  STFC/RAL, Chilton, Didcot, Oxon
• W.A. Gillespie
  University of Dundee, Nethergate, Dundee, Scotland
• S.M. Hooker
  OXFORDphysics, Oxford, Oxon
• T. Ibbotson
  University of Oxford, Clarendon Laboratory, Oxford
• A. MacLeod
  UAD, Dundee
• D. Maneuski, V. O'Shea
  University of Glasgow, Glasgow
• M.W. Poole
  STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

We describe the latest results to develop brilliant incoherent and coherent radiation sources based on laser-plasma wakefield accelerators. We demonstrate both experimentally and theoretically a brilliant gamma ray sub 10 femtosecond source based on betatron radiation in the plasma density wake trailing behind an intense laser pulse. Furthermore, experimental and theoretical progress towards a compact free-electron laser based on a laser-plasma wakefield accelerator will be discussed.

• S.I. Bajlekov, S.M. Hooker
  University of Oxford, Clarendon Laboratory, Oxford
• R. Bartolini
  Diamond, Oxfordshire

Ultrashort electron bunches from laser-driven plasma accelerators hold promise as drivers for short-wavelength free electron lasers*. While full 3-D FEL simulation techniques have been successful in simulating lasing at present-day facilities, the novel sources investigated here are likely to violate a number of widely-held assumptions. For instance the HHG seed radiation, as well as the radiation generated by the bunch, do not conform to the slowly-varying envelope approximation (SVEA) on which the majority of codes are based. Additionally, the longitudinal macroparticle binning precludes the full physics of the system from being modeled. In order to more completely simulate the arising sub-wavelength effect we have developed an unaveraged 1-D time-dependent code without the SVEA. We highlight some of the additional features that these new systems present through analytical and numerical analyses. We discuss the regimes in which these effects become important, and investigate how they may be used to enhance the lasing process. Finally we outline a framework for full 3-D simulation of a short-wavelength FEL driven by a laser-plasma accelerator.

* Leemans et al., Nat. Phys. 2, 696 (2006); Gruner et al., Appl. Phys. B 86, 431 (2007).